Measuring the decoherence rate in a semiconductor charge qubit

We describe a method by which the decoherence time of a solid-state qubit may be measured. The qubit is coded in the orbital degree of freedom of a single electron bound to a pair of donor impurities in a semiconductor host. The qubit is manipulated by adiabatically varying an external electric field. We show that by measuring the total probability of a successful qubit rotation as a function of the control field parameters, the decoherence rate may be determined. We estimate various system parameters, including the decoherence rates due to electromagnetic fluctuations and acoustic phonons. We find that, for reasonable physical parameters, the experiment is possible with existing technology. In particular, the use of adiabatic control fields implies that the experiment can be performed with control electronics with a time resolution of tens of nanoseconds.

Sensitization to foods in gastroesophageal reflux disease and its relation to eosinophils in the esophagus: is it of clinical importance?

Background: Refractory gastroesophageal reflux disease (GERD) can be related to greater sensitization to foods. Objective: To evaluate sensitization to foods in patients with refractory GERD. Methods: Patients with refractory GERD after using at least 40 mg of a proton pump inhibitor were given a restriction diet based on the results of skin prick testing and atopy patch testing with foods. The characteristics of sensitized patients were compared with those of nonsensitized patients in relation to atopy and number of eosinophils in the esophageal mucosa. Results: The prevalence of sensitization to foods was 27.7%. Asthmatic patients showed higher sensitization to foods (P = .008). Eosinophils were determined to be present in the esophageal mucosa in 15.8% of patients, and this correlated with greater sensitization to foods (P = .01). One case of eosinophilic esophagitis was confirmed. A diet excluding identified sensitizing foods led to clinical improvement regarding GERD symptoms (P = .004). Conclusion: The presence of eosinophils in esophageal mucosa associated with greater sensitization to foods and the response to a restriction diet in patients with positive test results suggest that refractory GERD can represent an initial stage of eosinophilic esophagitis. Ann Allergy Asthma Immunol. 2010;105:359-363.

Fascicular Topography of the Suprascapular Nerve in the C5 Root and Upper Trunk of the Brachial Plexus: A Microanatomic Study From a Nerve Surgeon`s Perspective

BACKGROUND: In patients with supraclavicular injuries of the brachial plexus, the suprascapular nerve (SSN) is frequently reconstructed with a sural nerve graft coapted to C5. As the C5 cross-sectional diameter exceeds the graft diameter, inadequate positioning of the graft is possible. OBJECTIVE: To identify a specific area within the C5 proximal stump that contains the SSN axons and to determine how this area could be localized by the nerve surgeon, we conducted a microanatomic study of the intraplexal topography of the SSN. METHODS: The right-sided C5 and C6 roots, the upper trunk with its divisions, and the SSN of 20 adult nonfixed cadavers were removed and fixed. The position and area occupied by the SSN fibers inside C5 were assessed and registered under magnification. RESULTS: The SSN was monofascicular in all specimens and derived its fibers mainly from C5. Small contributions from C6 were found in 12 specimens (60%). The mean transverse area of C5 occupied by SSN fibers was 28.23%. In 16 specimens (80%), the SSN fibers were localized in the ventral (mainly the rostroventral) quadrants of C5, a cross-sectional area between 9 o`clock and 3 o`clock from the surgeon`s intraoperative perspective. CONCLUSION: In reconstruction of the SSN with a sural nerve graft, coaptation should be performed in the rostroventral quadrant of C5 cross-sectional area (between 9 and 12 o`clock from the nerve surgeon`s point of view in a right-sided brachial plexus exploration). This will minimize axonal misrouting and may improve outcome.

The paraventricular nucleus of the hypothalamus is involved in cardiovascular responses to acute restraint stress in rats

The paraventricular nucleus of the hypothalamus (PVN) has been implicated in several aspects of cardiovascular control. Stimulation of the PVN evokes changes in blood pressure and heart rate. Additionally, this brain area is connected to several limbic structures implicated in behavioral control, as well as to forebrain and brainstem structures involved in cardiovascular control. This evidence indicates that the PVN may modulate cardiovascular correlates of behavioral responses to stressful stimuli. Acute restraint is an unavoidable stressor that evokes marked and sustained cardiovascular changes, which are characterized by elevated mean arterial pressure (MAP) and an intense heart rate (HR) increase. We report on the effect of inhibition of PVN synapses on MAP and HR responses evoked by acute restraint in rats. Bilateral microinjection of the nonspecific synaptic blocker cobalt (CoCl2, 1mM/100nl) into the PVN did not change the HR response or the initial peak of the MAP response to restraint stress, but reduced the area under the curve of the MAP response. Moreover, bilateral microinjection of cobalt in areas surrounding the PVN did not change the cardiovascular response to restraint. These results indicate that synapses in the PVN are involved in the neural pathway that controls blood pressure changes evoked by restraint.

Modeling the Dynamics of Viral Evolution Considering Competition Within Individual Hosts and at Population Level: The Effects of Treatment

We consider two viral strains competing against each other within individual hosts (at cellular level) and at population level (for infecting hosts) by studying two cases. In the first case, the strains do not mutate into each other. In this case, we found that each individual in the population can be infected by only one strain and that co-existence in the population is possible only when the strain that has the greater basic intracellular reproduction number, R (0c) , has the smaller population number R (0p) . Treatment against the one strain shifts the population equilibrium toward the other strain in a complicated way (see Appendix B). In the second case, we assume that the strain that has the greater intracellular number R (0c) can mutate into the other strain. In this case, individual hosts can be simultaneously infected by both strains (co-existence within the host). Treatment shifts the prevalence of the two strains within the hosts, depending on the mortality induced by the treatment, which is, in turn, dependent upon the doses given to each individual. The relative proportions of the strains at the population level, under treatment, depend both on the relative proportions within the hosts (which is determined by the dosage of treatment) and on the number of individuals treated per unit time, that is, the rate of treatment. Implications for cases of real diseases are briefly discussed.

PCR in the First Oropharynx Aspirate of the Newborn: A Possible Source for Identification of Congenital Infection Agents

We present a case of prenatal diagnosis of congenital rubella. After birth, in addition to traditional serologic and clinical examinations to confirm the infection, we could identify the virus in the "first fluid aspirated from the oropharynx of the newborn", using polimerase chain reaction (PCR). We propose that this first oropharynx fluid (collected routinely immediately after birth) could be used as a source for identification of various congenital infection agents, which may not always be easily identified by current methods